U.S. patent number 3,708,250 [Application Number 05/080,382] was granted by the patent office on 1973-01-02 for regulated radial piston pump.
Invention is credited to Fritz Thumm.
United States Patent |
3,708,250 |
Thumm |
January 2, 1973 |
REGULATED RADIAL PISTON PUMP
Abstract
A radial piston pump has a rotor with working chambers and
pistons or vanes in the same whose outer ends have shoes sliding on
a circular guide ring mounted eccentrically to the rotor axis on a
tiltable support whose angular position, and thereby the
eccentricity of the guide ring, is varied by a setting device
including a hydraulic motor angularly displacing the tiltable
support under the control of a valve which is operated by a control
circuit.
Inventors: |
Thumm; Fritz (Urach,
DT) |
Family
ID: |
22157027 |
Appl.
No.: |
05/080,382 |
Filed: |
October 13, 1970 |
Current U.S.
Class: |
417/221 |
Current CPC
Class: |
F04B
49/08 (20130101); F04B 1/0439 (20130101); F04B
49/06 (20130101); F04B 49/128 (20130101); F04B
1/1071 (20130101); F04B 1/07 (20130101); F04B
49/002 (20130101) |
Current International
Class: |
F04B
1/107 (20060101); F04B 1/04 (20060101); F04B
1/00 (20060101); F04B 49/08 (20060101); F04B
49/06 (20060101); F04B 49/12 (20060101); F04B
49/00 (20060101); F04b 001/06 () |
Field of
Search: |
;91/497,498 ;92/12.1
;417/221 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Freeh; William L.
Claims
I claim:
1. Regulated readial piston pump, comprising, in combination,
casing means; journal means mounted in said casing means and having
inlet duct means and outlet duct means; driven rotor means mounted
on said journal means for rotation about a rotor axis, and
including a cylindrical control bushing surrounding said journal
means in the region of said ports and forming a thin annular
leakage gap with said journal means in which said duct means
communicate so that said control bushing floats on said journal
means, and a rotor having working chambers communicating with said
duct means, and piston means radially movable in said working
chambers and having outwardly located guide parts; two roller
bearings located on said journal means on opposite sides of said
control bushing and supporting said rotor for rotation; tiltable
support means having a support part for mounting said support means
on said casing means for angular movement about a pivot axis
parallel to said rotor axis, and an operating part; guide ring
means rotatably supported on said tiltable support means
eccentrically surrounding said rotor and having an annular guide
surface slidingly engaged by said guide parts of said piston means
so that said piston means are operated during rotation of said
rotor means; and a regulating setting device mounted on said casing
means and including movable control means engaging said operating
part for angularly shifting the same with said support means and
said guide ring means about said pivot axis between positions of
different eccentricity of said annular guide surface in relation to
said rotor axis.
2. A pump as claimed in claim 1, wherein said rotor means include a
driven shaft coaxial with said journal and disposed in end-to-end
relation with the same, comprising coupling means including two
coupling members secured to said drive shaft and to said rotor,
respectively, said coupling members having hardened
part-cylindrical guideways crossing each other at an angle of
90.degree., part cylindrical slide block means slidingly mounted in
said guideways and consisting of a soft material, and a coupling
part having crossing prismatic portions projecting into
corresponding crossing recesses in said slide blocks.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a radial piston pump of the type
in which the rotor is mounted on a journal and driven by a drive
shaft. Inlet ducts and outlet ducts are provided in the journal for
supplying a fluid such as oil to the chambers in the rotor. An
eccentric guide ring is provided along which the pistons slide so
that the same are moved into and out of the rotor chambers during
rotation of the rotor.
Known pumps of this type have the disadvantage that the speed at
which they can be adjusted, as well as the span of life of the
entire pump, and also of individual parts of the same is
comparatively short. Thereby, the purposes for which the pumps can
be used are limited, and on the other hand pumps of this type
cannot be used in arrangements in which a continuous operation of
the pump is required.
SUMMARY OF THE INVENTION
It is the main object of the invention to provide a radial piston
pump which has a very long span of useful life also at high
pressures.
Another object of the invention is to provide a radial piston pump
which can be regulated at very high speed by means of exchangeable
control and setting devices.
With these objects in view, an embodiment of the invention
comprises a casing, a journal mounted in the casing and having
inlet and outlet ducts, driven rotor means mounted on the journal
for rotation, and including a rotor having working chambers
communicating with the ducts, and pistons movable in the working
chambers, and having outwardly located slide shoes, tiltable
support means mounted on the casing for angular movement about a
pivot axis parallel to the rotor axis, a guide ring rotatably
supported on the tiltable support means eccentrically surrounding
the rotor and having an annular surface slidingly engaged by the
slide shoes of the pistons so that the pistons are operated, and a
setting device mounted on the casing and including movable control
means engaging the tiltable support means for angularly shifting
the same with the guide ring about the pivot axis between positions
of different eccentricity in relation to the rotor axis.
The rotor means preferably include a driven shaft coaxial with the
journal and disposed in end-to-end relation with the same, and a
connecting coupling.
The casing means include a detachable part supporting the setting
device, so that the same can be removed, exchanged or replaced, and
then again mounted on the casing in an operative position.
The driven rotor shaft preferably drives auxiliary pumps, which
include a lubricating pump pumping lubricating oil to several
bearings of the pump.
The guide ring, along which the pistons slide, is mounted in the
tiltable support by means of two symmetrically arranged roller
bearings which are located laterally of the plane of the rotor, and
support smaller diameter portions of the guide ring means whose
diameter is selected to permit displacement of the guide ring with
the tiltable support means without interference with the rotor
shaft and with the rotor supporting journal which pass through the
center of the guide ring means eccentrically to the same. Due to
the fact that the portions of the guide ring means which are
mounted on bearings, have the smallest possible diameter, smaller
than the diameter of the guide surface of the guide ring, the
rotary speeds occurring at the bearings are small as compared with
prior art constructions in which the guide ring is mounted on outer
peripheral portions of the casing, so that the span of life of the
respective bearings supporting the guide ring is comparatively
long.
The pistons in the working chambers of the rotors are connected
with a cross head on which a slide shoe is mounted for angular
movement. The cross head has a portion which has a diameter greater
than the piston diameter, so that forces transmitted from the slide
shoe to the cross head are completely taken up by the cross head
and transferred to the guide ring so that no lateral forces act on
the pistons whose life span is thus increased.
The drive shaft which drives the rotor is connected with the same
by a coupling of the Oldham type which permits relative movement,
and has slide blocks preferably consisting of bronze so that the
coupling can be serviced by exchanging only the slide blocks.
In accordance with the preferred embodiment of the invention, a
control bushing surrounds the journal in the region of the ports of
the inlet and outlet ducts and permits along the circumference and
axial width thereof an equalizing of the pressure on the surface of
the journal so that the control bushing floats on the journal. In
axial direction, roller bearings are arranged on opposite sides of
the control bushing which, due to the pressure equalization within
the control bushing, only serve the purpose of guiding the rotor on
the journal. This construction again assures a long span of life of
the pump.
In the preferred embodiment of the invention, a drive gear is
driven by the rotor shaft which meshes with one or several pinions
mounted within the casing and having shafts projecting out of the
same for driving the rotors of auxiliary pumps whose housings are
secured to the casing of the main pump. The auxiliary pumps may
include a lubricating pump for pumping lubricating oil to the
bearings of the pump, and another auxiliary pump providing pressure
fluid for the setting device which includes a hydraulic piston and
cylinder motor and a valve for operating the same, and thereby the
tiltable support means with the eccentric guide ring. Lubricating
ducts in the journal supply the lubricating oil to the bearings on
opposite sides of the control bushing, and also to the guide
surface on which the shoes of the pistons slide. Due to the forced
lubrications at the mentioned parts of the pump, a perfect
lubrication is assured even if the pump operates for a long time
without any load, when leakage oil lubrication is no longer
assured.
The setting device may be controlled by hydraulic, pneumatic,
electric or mechanical control mechanism which controls the control
means by which the tiltable support means is angularly displaced
with the guide ring so that the same has a desired
eccentricity.
Due to the above explained constructive features of the movable
parts of the pump, and of the bearings and coupling of the same,
radial piston pumps in accordance with the invention, have a very
long span of life even at high operational pressures. Due to the
mounting of the tiltable support means, and of the settling device
for the same, the pump can be very rapidly adjusted so that a pump
according to the invention can be used for large jarring machines
in which a quick and continuous shifting of the pump has to be
carried out. Pumps according to the present invention can be
controlled at regulating speeds above 60 milliseconds, and operate
at pressures up to 350 atmospheres, and peak pressures of 400
atmospheres.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an end view, and partially a section along line I--I in
FIG. 2, and illustrating an embodiment of the invention;
FIG. 2 is an axial sectional view taken on line II--II in FIG.
1;
FIG. 3 is a sectional view illustrating a coupling means used in
the embodiment of FIGS. 1 and 2;
FIG. 4 is a fragmentary cross-sectional view on a larger scale,
illustrating a detail;
FIG. 4a is a fragmentary axial sectional view taken on line
IVa--IVa in FIG. 4;
FIG. 5 is a fragmentary sectional view, illustrating the setting
device of the pump on an enlarged scale;
FIG. 6 is a diagram illustrating the hydraulic and electric
connections of the pump and the setting device thereof; and
FIG. 7 is a diagram illustrating the hydraulic and electric
connection of the pump, and of a modified setting device
thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The pump illustrated in the drawings, has a pump casing 1 which is
integral with a base portion 1a. One side of the casing 1 is closed
by a cover 2 which extends down to the base casing portion 1a.
Cover 2 has a comparatively long hub portion 2a in which a shaft 3,
driven by a prime mover, not shown, is mounted on two roller
bearings 4 and 5 which are arranged spaced a substantial distance
in axial direction from each other. In this manner, shaft 3 is
reliably supported, and the coupling, shown at 6 in FIG. 2 and
better shown in FIG. 3 is relieved of transverse forces. In the
region of the inner end of shaft 3, a gear 7 is mounted which
meshes with several gears which are mounted within the cover 2,
only one gear 8 being shown for the sake of simplicity.
The shafts of gears 8 project through openings in cover 2, and are
connected by plug and socket couplings 11 with the rotors of
auxiliary pumps 10 whose housings are mounted on the outside of
cover 2 in such a manner that the auxiliary pumps 10 can be
replaced.
The auxiliary pump 10 shown in FIG. 2 functions as a lubricating
pump and delivers through a lubricating duct 12, shown as a chain
line, lubricating oil through a duct 13 in the journal 14 of the
pump. Another auxiliary pump, not shown in FIG. 2 supplies oil to
the hydraulic motor of a setting device 15 which is exchangeably
mounted on the casing, as will be described in greater detail with
reference to FIGS. 5 to 7.
Pump casing 1 has a tubular end portion 1b into which the
stationary journal 14 of the pump is inserted. Inlet and outlet
ducts are provided in journal 14, and communicate with the inlet
means 19 and outlet means 17. The other ends of the inlet and
outlet ducts terminate in circumferential ports 18 and 16 which
cooperate with a circular control bushing 21 which surrounds the
respective peripheral portion of the journal 14. Control bushing 21
is formed with openings which control the flow of oil into the
chambers of a rotor 20 which is mounted on journal 14 by means of
control bushing 21, and two roller bearings 22 and 23 on opposite
sides of control bushing 21. The control bushing 21 forms a small
annular gap with the journal 14, so that there is some leakage
communication between the inlet and outlet ducts, for equalizing
the pressure within the gap whereby the control bushing 21 floats
on the journal 14. The play between control bushing 21 and journal
14 is determined by the lateral precision bearings 22 and 23, which
serve only the purpose of guiding the rotor. Due to this bearing
arrangement, a uniform very small leakage loss is assured during a
long term of operations of the pump.
As best seen in FIGS. 4 and 4 a, pistons 40, which are guided in
radially extending working chambers of rotor 20, are connected by a
cross head 41 with pairs of slide shoes 42 which slide on
intermediate rings 43 of the guide ring means 24. The cross heads
41 are mounted in rotor 20, and have in the bearing region, a
greater diameter than the pistons 40. By this construction it is
assured that non-radial forces acting on the unit formed by slide
shoe 42, cross head 41, piston 40, and piston pin 44, are taken up
by the cross head, and do not act on the respective piston 40,
which assures a long span of life for the pistons, even if the pump
is operated at very high pressure.
The intermediate rings 43 of the guide ring means 24, have inner
cylindrical surfaces on which the shoes 42 slide, and since the
center of the guide surfaces of rings 43 is eccentric to the axis
of the journal 14 about which rotor 20 rotates, the pistons are
moved into and out of the working chambers which are thus
contracted or expanded for pumping the fluid, depending on the
eccentricity of the guide surfaces of rings 43. A pair of tiltable
supports 27 is mounted on a pivot 30 which is rotatably supported
by bearings 28 and 29 in the base portion 1a of the casing.
Diametrically opposite the support portion of supports 27 and pivot
30, a pin 31 connects the two supports 27, and is engaged by a
piston 60 which is movable in a cylinder 62 of a hydraulic motor,
as best seen in FIG. 1. Consequently, supports 27 can be together
tilted about the axis of pivot 30.
Supports 27 have large central openings in which roller bearings 26
and 27 are located whose inner races are secured to annular lateral
portions of the guide ring means 24 which are located in opposite
sides of the rotor. The lateral annular parts of the guide ring
means 24 have equal inner diameters, and surround the shaft 3 and
journal 19, respectively. The diameters of the lateral annular
portions of the guide ring means 24 are selected so that the
annular lateral portions do not engage or interfere with shaft 3
and journal 19 when the tiltable supports 27 are displaced together
with the guide ring means 24 for adjusting the eccentricity of the
same in relation to the axis of shaft 3 and journal 19, as required
for the regulation of the pump. Due to the comparatively small
diameter of the annular lateral portion as compared with the
central guide portion of the guide ring means 24, the rotary speed
of the roller bearings 26 and 25 is small, since the same have the
smallest possible diameter.
A lubricating conduit 13 in journal 19 has outlet openings 13a in
the region of the roller bearings 22, 23, and furthermore an outlet
13b radially projecting adjacent rotor 20, which supplies
lubricating oil into the guide ring means 24, particularly for
supplying lubricating oil to the slide shoes 42. The lubricating
conduit 13 is connected with one of the auxiliary pumps 10 which
are driven by rotor shaft 3.
FIG. 3 illustrates a coupling of the Oldham type which connects
shaft 3 with a hub portion 20a of rotor 20, and compensates
displacements of shaft 3 relative to journal 14. The coupling has
part-cylindrical slide blocks 50 consisting of a bearing metal, for
example bronze, and engaging corresponding part-cylindrical
recesses 51 and 52 in the coupling portion 20a of rotor 20, and in
a coupling portion of drive shaft 3. The coupling part 6 between
the recesses 51 and 52 is a hardened metal, so that a long span of
life of the coupling is assured. Coupling part 6 has projecting
prismatic portions 6a located in corresponding inner recesses of
slide blocks 50. The outer surfaces of slide blocks 50 have grooves
50c engaged by portions 50b of members 50a which are secured to
shaft 3 and hub portion 20a, respectively, for preventing axial
sliding of slide blocks 50. After a long time of use, only the
slide blocks 50 are worn, and can be easily replaced.
In FIGS. 1 and 2, a setting device 15 is shown to be mounted on the
detachable cover 15a of the casing 1, whose control piston 60 has a
cutout 61 engaging the bolt 31 connecting the upper portions of the
tiltable supports 27. The control piston 60 forms the chambers in
cylinder 63 on opposite sides thereof, to which fluid is supplied,
and from which fluid is exhausted in order to displace the tiltable
supports 24. The unit can be removed together with cover 15a, and
another unit can be substituted, depending on the manner of
regulation of the pump which is intended.
FIGS. 5 to 7 show regulating devices 15'.
As shown in FIG. 5, the setting device 15' is controlled by the
circuit shown in FIG. 6 for controlling the volume of fluid pumped
by the pump. The setting device 15' is schematically indicated by a
chain line in FIG. 6. The pump P, as shown in FIGS. 1 and 2,
operates an auxiliary pump 11, see also FIG. 2, which supplies oil
into the setting device 15', and is driven from gear 7 through gear
8. The casing cover 15'a of the setting device 15' also supports a
hydraulic slide valve 64, an excess pressure valve 65, and an
electrical distance indicator 66. Valve 64 is electromagnetically
operated, and the control slide 67 has at opposite ends thereof,
armature portions for electromagnets 68 and 69, see also FIG. 6 in
which the valve 64 is schematically indicated in three control
positions.
The distance measuring and indicating device 66 may include a
potentiometer, as shown in FIG. 6, or an adjustable inductive
resistance whose movable tap is connected by a pin 70 with a
double-armed lever 72 turnable about a pivot 71. Consequently, the
movements of control piston 60, which corresponds to the movements
of the guide ring means 24, are transmitted to the turnable member
of the potentiometer 66.
Control valve 64 has a central position in which conduit 74 is
separated from conduit 76, and conduit 73 is separated from conduit
75. In the first control position of the slide valve, conduit 73 is
connected with conduit 75, and conduit 74 is connected with conduit
76. In the third control position of slide valve 64, conduit 75 is
connected with conduit 74, and conduit 73 is connected with conduit
76, as schematically shown in FIG. 6. Conduits 73 and 74 are
connected with the chambers 62 formed in cylinder 63 on opposite
sides of control piston 60. Conduit 75 has a connecting point 79 at
which the excess pressure valve 65 is connected, and conduit 76
also has a connecting point 80, and is connected at the outlet 81
with a conduit 83 connected with the suction inlets of pump P and
of auxiliary pump 11, which communicate with a container 82. When
slide 67 is shifted by electromagnetic means 68 or 69 to the left,
a connection between conduit 75 and conduit 73 is established so
that pressure oil flows into chamber 62 and moves the control
piston 60 to the right as viewed in FIG. 5, while the conduit 74 is
connected with the other chamber and with the return conduit 76 so
that the oil can flow out of the other chamber of cylinder and
piston means 60. When slide 67 is moved to the right, the
connections are reversed, and control piston 60 is moved to the
left. The oil is pumped from auxiliary pump 11 through the
connecting point 78 into the regulating device 15', where the
pressure conduit 75 is connected at the point 79 with the excess
pressure valve 65.
The regulating device is controlled by an electric control circuit
which includes an operation amplifier 84 designed as a comparison
device, which is known, and not an object of the invention. The
desired amount of volume of fluid which is to be delivered by pump
1, is selected at an electrical device, not shown, which generates
on line 85 a signal indicating the desired volume, and this signal
is supplied to the comparison amplifier 84 while the actual
position of control piston 60 is represented by a signal generated
by the distance measuring means 66. Operation amplifier 84 produces
a differential signal which causes energization of either
electromagnet 68 or electromagnet 69 for displacing the valve slide
64 accordingly. In this manner, oil is directed into one of the two
cylinder chambers 62 for shifting control piston 60 for angularly
displacing the guide ring means 24 about the pivot axis 30 together
with the supports 27 so that the volume delivered by the pump is
varied. The displacement of control piston 60 is measured by the
distance indicator 66 which causes a corresponding change of the
signal thereof representing the actual position, until this signal
corresponds fully to the signal representing the desired position
and volume of fluid. At the moment when equality is reached, the
slide 67 of valve 64 is returned to its position of rest in which
the connecting conduit 73 to the two chambers 62 of cylinder 63 are
closed.
A variation of the delivered volume makes many uses possible for
the pump, particularly with apparatus which have a numerically
controlled sequence of operations. A linear variation of the pumped
amount in accordance with the value represented by an electric
comparison signal representing a desired amount can be obtained,
and small control voltages are sufficient to regulate the pump in a
short period of time from idling to maximum delivered volume. The
regulating time is only between 25 and 60 milliseconds, depending
on the size of the pump.
The exchangeable and replaceable regulating devices 15, 15' cannot
only effect a variation of the volume of the pumped fluid, but may
also be constructed so that the volume can be varied depending on
the pressure, or so that the volume is maintained constant,
independently of the pressure.
As shown in FIg. 7 a measuring turbine 87 can be provided in the
output conduit 88 of the pump P which produces a signal depending
on the volume of oil flowing in outlet conduit 88, and supplies
this signal through an electric connector 89 to the only partly
shown electrical part of the regulating device so that the pump is
regulated in a manner which assures the maintaining of a constant
pumped and delivered volume, independently of the pressure, which
develops in the outlet line 88 dependent on the load determined by
a consumer apparatus connected to the outlet conduit 88 of pump
P.
The modified electrical control circuit shown in FIG. 7
additionally includes a pressure measuring valve 90 which is loaded
by a spring 95 and has a spring biassed piston 92. Piston 92 limits
a cylinder chamber 93 which is connected by an oil conduit 94 to
the outlet conduit 88 of the pump. The piston 92 is further
connected with the movable member 94 of a variable resistor 95,
which is constructed similar to the distance measuring device 66
shown in FIG. 5, and which supplies through an electric conductor
98 another signal to the operation amplifier 84, this signal
depending on the pressure in the outlet conduit 88. The pressure
responsive device 90 with the variable resistor 95 constitute a
modulating control means whose regulating or control signal can be
used for regulating a part of the load of the pump. The pressure
responsive means 90 creates a pressure controlling signal, while
the measuring turbine 87 creates a volume return signal for the
regulating device, which is important for the compensation of
leakage oil losses.
It will be seen that the pump of the invention can be adapted by
means of an exchangeable regulating device to many complex uses,
and can be regulated at a very high speed, even beyond the zero
point of regulation between reversed conditions.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of radial piston pumps differing from the types described
above.
While the invention has been illustrated and described as embodied
in a radial piston pump in which the eccentric guide ring is
pivotally mounted for angular adjustment, and controlled by a
regulating setting device responding to electrical signals, it is
not intended to be limited to the details shown, since various
modifications and structural changes may be made without departing
in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can by applying current
knowledge readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention and, therefore, such adaptations should
and are intended to be comprehended within the meaning and range of
equivalence of the following claims.
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims.
* * * * *